PERIODICALLY, at intervals, on and off, (every) once in a while, every so often, (every) now and then/again, from time to time, occasionally, sometimes, intermittently, irregularly.
2192; headword
OFF AND ON
Meaning of OFF AND ON in English
Concise Oxford thesaurus English vocabulary. Краткий оксфордский словарь английского языка тезаурус. 2012